1. Field of the Invention
The invention relates to electric lamps and particularly to electric lamps using LEDs as light sources. More particularly the invention is concerned with optical element for use in a vehicle high mounted stop lamp with an LED as a light source.
2. Description of the Related Art Including Information Disclosed under 37 CFR 1.97 and 1.98
Current LED based center high mounted stop lamps (CHMSLs) use from 4 to 24 LED's depending on the their efficiency. The lamp cost is substantially determined by the number of LEDs used, so there is a need to reduce the number of LED needed in the lamp. One LED would be ideal. On the other hand there is a legal requirement that the available light from the CHMSL be dispersed over an area. This is so that viewers are not blinded by a point source, and also to assure human detection and shorten the response time, results that occur with a large area of illumination. There is then a need to meet the minimal standards for area and illumination for CHMSLs.
A simple solution is to install a single bright LED in a parabolic reflector. The depth and diameter of the reflector would be substantial, and therefore impractical for the typical preferred mounting sites on the window or in the vehicle body wall. The main problem is the depth required for such a design. There is then a need for relatively flat optical element that functions as a CHMSL.